1. Field of the Invention
The present invention relates to a stage, and more particularly to a stage with a simplified structure for a centrifugal submersible pump.
2. Description of Related Art
With reference to FIGS. 3 and 4, a conventional stage for a centrifugal submersible pump comprises a base (40) and an impeller (30). The base (40) is a segmented hollow cylinder with a top end and a bottom end. Multiple spiral ribs (41) are integrally formed in the base (40). A flange (42) is formed on the top end of the base (40). A central hole (43) is defined through the top flange (42). The impeller (30) has multiple vanes (32) in the impeller (30). The impeller (30) is rotatably supported on the top flange (42) of the base (40). An annular lip (31) extends from the bottom of the impeller (30) and into the central hole (43) in the base (40).
In use, the impellers (30) of multiple stages are pressed onto a shaft (300) extending from a motor (not shown) for the centrifugal submersible pump. When the motor is switched on, the impellers (30) will rotate with the shaft (300). A water vortex will be generated along the ribs (41) in the base (40) by the vanes (32) in the impeller (30), and the water is pressurized. Consequently, the water in the deep can be pushed to a high level.
However, the conventional stage has the following shortcomings:
1. Because the ribs (41) and the top flange (42) of the base (40) must be fabricated in a casting process, the structure of the base (40) and the mold to form the base (40) are complex. A particular problem is that each rid (41) in the base (40) must be formed with a spiral or curved shape to provide the least resistance while guiding the water vortex to the impeller inlet. To form the conventional base (40) is very difficult and expensive.
2. The base (40) and the impeller (30) are made of metal materials. The impeller (30) is supported on the top flange (42) of the base (40), and the lip (31) on the base (30) extends into the central hole (43) in the base (40). Therefore, the top flange (42) of the base (40), the inner surface of the central hole (43) in the base (40), the bottom of the impeller (30) and the lip (31) are easily worn down as the impeller (30) rotates relative to the base (40). The useful life of the stage is short.
To overcome the shortcomings, the present invention provides an improved stage to mitigate or obviate the aforementioned problems.
The main objective of the invention is to provide an improved stage for a centrifugal submersible pump to simplify the structure of the stage and the process for manufacturing the stage. The stage has a segmented base, a connecting plate and an impeller. The segmented base has an open top end, an open bottom end and multiple spiral ribs integrally formed in the base. The connecting plate is securely attached to top end of the base. The connecting plate has an annular core and a resilient coating. The coating is coated around the core and pressed into the top of the base. A central hole is defined through the resilient coating. The impeller is rotatably supported on the connecting plate. Accordingly, the structure of the base is simplified. The cost for manufacturing the stage is reduced. In addition, because the metal impeller will not abut the metal base but supported on the connecting plate having the resilient coating, the wear between the base and the impeller can be prevented. Only the coating on the connecting plate will wear, and the connecting plate can be replaced to restore the pump to full operations without having to replace the base and the impeller.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.